Femto Cells Attributes And Issues Computer Science Essay

Femtocells are low power entree point, based on the nomadic engineering in order to supply dependable coverage in place and office environment by linking to the cellular operator ‘s web through a wide set connexion. The operator nucleus web contains a direction system which provides services to the femtocell, guaranting that the services experienced by the users are unafraid, of high quality and can coexist with the signals from other femtocells and out-of-door web. The processing mechanisms are simple which consumes less power and provides inexpensive communicating.

In this paper, a complete reappraisal of the femto cells is undertaken by throwing visible radiation on its properties, web architecture and issues.

Cellular engineering is one of the fastest turning engineerings in the universe and depending upon its publicities its informations traffic is expected to increase by 10 times between 2008 and 2013 [ 1 ] book. Internet is following with 1.6 billion users worldwide. The voice services of cell phones were merged with informations services of cyberspace in 3G services.

Acceleration was observed in both, the broadband informations consumed and the generated grosss. Operators are working to diminish the cost per spot of delivered informations for accomplishment of higher net income borders. Cellular engineering is non merely used by people on move but besides by the individuals at place or workplace for privateness although webs are non designed for solid residential services. Using a macro cell for the bringing of acceptable residential coverage is non an effectual solution from both coverage and economic position. Poor perforating ability through constructions like walls due to higher runing frequences of 3G is another ground for endorser dissatisfaction.

The acceptance of complex cryptography and transition strategies to accomplish higher information rates brings greater public presentation punishments to 3G, LTE and WI-Max.

Deployment of microcell in high capacity locations like offices and metropolis Centres was justified by gross generated but when it comes to home the job was still at that place as the deployment of separate base Stationss in places and little offices seemed impossible merely a few old ages back. Presents industry is concentrating on better residential coverage for capturing market portion. A complete solution of indoor coverage issue is achieved with the aid of femto cell web design. By rescue of better services to stop users and increased grosss to operators, femto cells are deriving importance in industry as portion of future web architectures.

Properties

Femto cell is a low power radio entree point which operates on standard radio protocols like GSM, LTE and Mobile Wi-Max, to pass on with a broad scope of Mobile enabled devices, which enable femto cells to supply services to one million millions of bing nomadic devices that users can entree from about any location as portion of a wide-area web. . By runing in spectrum licensed to the service supplier, femto cells provide assured quality of service without any harmful intervention but doing efficient usage of their spectrum. Along with coverage betterment it besides creates excess web capacity by functioning a greater figure of users with high informations rates. Femto cells are installed by the clients nevertheless they continue to set themselves over clip as the client and operator supplications to maximize public presentation and dependability. The operator is ever able to make or deny service to single femtocells or users. This control is maintained whether the femtocell is owned by the receiving system or stop user.

The radiated power and user capacity supported by a femto cell varies from one category to another. Class 1 emerged first and is best known which transmits 20dBm of power and supports 4-8 voice calls and informations services and is considered best for little places or endeavor. Class 2 may be viewed as an development of picocell engineering to fulfill 8-16 users and provides coverage for country larger as compared to category 1 by radiating higher power about 24dBm. Performance of 3rd category is better than the first two but it ‘s non used often.

Most air interfaces included in ITU-R IMT household have active programmes to develop criterions for femtocells. These include:

3GPP criterions for Home Node-B, which is a WCDMA femtocell. Both FDD and TDD options are likely and a TD-SCDMA discrepancy is besides planned.

3GPP criterions for Home Node-B, which is an LTE femtocell. Both FDD and TDD options are envisaged.

3GPP2 ‘s programme for femtocells for cdma2000, cdma2000 1x, HRPD, 1x EV-DO and UMB.

WiMAX Forum ‘s programme for WiMAX femtocells based on IEEE criterions.

III. NETWORK ARCHITECTURE

Femtocells will be deployed by the big figure of place users and endeavors in their premises. To suit 100s of 1000s of femto cells which are connected through cyberspace, the web architecture should run into the undermentioned demands:

Scalable to the big figure of femto cells units without upseting the bing web.

Seamless connectivity with any bing bequest operator substructure.

Since femtocells will be installed in the proprietor ‘s

premises, they should be easy configurable.

Femto web architecture should be to the full standardised to suit multi-vendor web. At least the following chief functional elements should be standardised [ 1 ] :

FEMTOCELL ACCESS POINT ( FAP ) is same as Base Station ( BS ) like in macro web. Its functionality is about same as BS like pass oning with Mobile Station and doing a connexion with Mobile Network Operator ( MNO ) Core Network ( CN ) [ 2 ] .

FEMTO GATEWAY ( FGW ) provides femtocell control, security and interfacing with MNO CN elements. A individual femto gateway can back up a big figure of FAPs [ 1 ] . FGW is composed of Security Gateway ( SeGW ) and Media Gateway ( MGW ) . The usage of FGW is optional in the criterion.

FEMTO MANAGEMENT SYSTEM ( FMS ) manages both the FAP and FGW. Its two chief functional elements are FAP Management system ( FAP-MS ) and FGW Management system ( FGW-MS ) . [ 1 ] It is besides used for configuring FAP via Fm interface ( new interface introduced in the femto forum mention theoretical account ) .

Typically we have two architectural picks whether to utilize a RAN based solution in which femto web integrates with macro web as being a portion of RAN or to utilize CN based solution in which femto web integrates with macro web as a CN component.

The undermentioned subdivision will depict the femtocell web architecture for CDMA 1x.

A. CDMA 1x Femto mention theoretical account

First consumer femtocells were offered by CDMA operators these deployments were for CDMA 1x RTT engineering ( 1x RTT is the version of CDMA 2000 which supports high informations rates ) . Architectural pick for CDMA was of CN based solution which uses IMS [ 1 ] . The mention diagram for CDMA 1x is shown in fig.

FAP is used for pass oning with the nomadic station. It besides set up a circuit ( voice and informations ) with the nucleus web.

FIG 1.1 CDMA 1x Femto Architecture

Femto Gateway ( FGW ) authenticates the FAP and manages the secure layers over the broadband IP nexus [ 1 ] . In FGW we have Security Gateway, It provides unafraid communicating between FAP and CN. IP Packets between FAP and CN are encapsulated in the IPSec tunnel which is provided by Fx3 between FAP and FGW [ 2 ] .

Telephony Application Server ( TAS ) provides maps tantamount to MSC in macro web. It provides processing every bit good as control for calls and other services.

FAP communicates with CN and TAS utilizing Fx1 and Fx2 interfaces.

MAP Femto interworking map ( MFIF ) provides internetwork signalling between FAP, IP Multimedia system ( IMS ) and CDMA nucleus web.

IV. ISSUES AND CHALLENGES

The set allocated to femto cells is already in usage by the bing macrocells so there is a high chance of intervention and wellness issues but rather different from those of macro cells due to their low scope and power degrees.

Health Issues

The bounds in the inquiry are based on the associated energy soaking up inside the human organic structure, measured in footings of specific soaking up rate. It is recognised fact that wireless frequence radiation does heat up local tissue, although the existent temperature rise depends on the rate at which heat is conducted off straight or by the flow of blood. Sellers are planing their merchandises to to the full follow with the usher lines for human exposure to electromagnetic emanations issued by International Commission on Non-Ionising Radiation Protection ( ICNIRP ) .

Lub over IP

Each femtocell is connected to the RNC via the standard lub interface. The lub protocol stack is encapsulated within IP signalling. The first chief concern is about whether RNC can back up 10s of 1000s of node-base Stationss that would be deployed in the femtocell web. Furthermore, despite being a standard interface, the lub has merely seller specific characteristics which are suited merely for equipment makers with an installed RNC base.

RF Issues

Signals produced by femtocells over the air interface are indistinguishable to those produced by conventional base station. However the intervention will be different to those of macrocells due to their little coverage country and this intervention is controlled by machine-controlled agencies alternatively of manual planning. Table shows a good comparing between different facets of both.

Table I

FEMTOCELL VS. MACROCELL [ 4 ]

Femtocell

Macro Cell

1

Air interface

Telecomm.

criterion

Telecomm.

criterion

2

Backhaul

Broadband

Internet

Telephone

Network

3

Cell phone power ingestion

low

high

4

Radio scope

10-50 metres

metres

Femtocell to Macrocell Interference: Femtocell can do intervention both on the UL and DL. For illustration, a femtocell installed near a window of a abode can do important DL intervention to the French telephones outside the house. On the UL, the place French telephones that are served by a certain femtocell can do important intervention to the macrocells. Therefore femtocell transmit power must be adjusted harmonizing to the macrocell power measured in the environing countries. In pattern, any macrocell users who encounter intervention would be switched to a different channel and would avoid outage from the femtocells.

Femtocell to Femtocell Interference: With the deployment of femtocell in next edifices or flats, it becomes relevant to see the co-channel intervention. Due to utilize of repeaters and macrocells intervention, the intervention degrees can make up to -65 dBm but femtocells are found to follow good to present coverage over the coveted countries with good public presentation in the presence of really strong co-channel intervention ensuing in high spectrum efficiency.

Security Issues

Since femtocells and femto-GWs communicate over public substructure alternatively of operator installed links. Communication services, voice and informations, must supply equal degree of security to transport messages to their finishs without modification- intentional or unwilled. Lack of security for a femtocell system would intend that the 3rd party will be able to detect, gaining control and analyze the information watercourse that flow in and out of the femtocell entree point ( FAP ) either over the wireless frequences used or via the informations nexus that carries IP connexions to the nucleus web. To supply safe communicating, hallmark and encoding must be done on the wireless nexus and IP backhaul.

E. Bandwidth Issues

Internet service suppliers ( ISPs ) provide asymmetric bandwidth to broadband users, with more bandwidth available on the downlink than the on the uplink. Hence, the figure of coincident users of a femtocell might be limited.

F. Handover

In order to supply seamless femto services to the users mobility to and from the macro web is one of the nucleus issues. When a femtocell user arrives at place unambiguous handoff should be made i.e. , seamless to the user as in macrocell webs.

When a femtocell French telephone arrives at place, services should be provided by the femtocell to the user non by the macro web, even if macrocell is supplying better signal so femtocell. Typically, the French telephone hunts for other frequences in instance the current macrocell signal is weak.

In the femto-to-macro handover instance, this can be easy done by spread outing the neighbour list which includes non merely the wireless features of the adjacent macrocells, but besides their full individuality. In the auto-configuration instance, FAP detects the macrocell individuality and so uses it during the handover process.

In the macro-to-femto handover instance it is impossible for the macrocell to cognize unequivocally the individuality of the femtocell to which it want to link because there can be 100s of femtocells in the country covered by a individual macro cell. Furthermore, if femtocells were to be known by individuality in the macrocells ‘ web, this would compare to an highly heavy and dynamic constellation attempt. Beacons can be radiated by femtocells to state the French telephone about its presence.

V. ADVANTAGES

With the betterment in indoor coverage femtocell makes it possible for high quality voice, informations and picture Sessionss to flux expeditiously, firmly and faithfully and this growing in information applications is besides accompanied by significant growing in informations gross, assisting to countervail the diminution in voice and day of the month grosss in many markets and to enable continued overall industry growing. They operate at low power degrees harmonizing to the parametric quantities assigned. Subscribers of femto cells enjoy a broad scope of possible services like particular call duties on all the calls made or received on the femtocell and place mechanization and security control along with higher information rates and quality coverage. Users are besides entertained with far higher usage bounds or even uncapped informations applications. The usage of DSL, overseas telegram or fiber, for the intent of connectivity to the nucleus web is really impressive as a resource is straight reused for which user has already paid beside the increased efficiency of service bringing for Mobile operators. The processing required for a femtocell is reduced as compared to a macrocell base station chiefly due to reduced capacity and a decreased demand to equalize the multipath channel. This is dominated by the decreased signal processing demands, particularly for the receiving system where maps such as correlators and Rake receiving systems have to run at high velocities. So a decreased processing power is required which decreases the entire cost per spot.

VI.DISADVANTAGES

A. Payment

Some cyberspace service suppliers ‘ programs charge on the footing of bandwidth used. Asking the endorser to pay extra charges for the extra capacity consumed for linking femtocells to the nucleus web may non be acceptable by the user.

B. Quality of Service

When femtocells are used to their full capacity, there might be a decrease in call quality/internet browse if immense files are downloaded.

C. Operational Requirement

Femtocells work merely for a peculiar cellular operator. So, everyone at place may necessitate to utilize the same operator and have to alter their Numberss which may impact their societal life.

D. Interface Problems

Not all cellular operators are on IP multimedia system ( IMS ) , which might go the interface for the femtocells.

Trouble-shooting

Cellular service suppliers are dependent on broadband services which are beyond their control. Any job in the cyberspace installation may convey a complete failure of cellular coverage inside places besides. So, trouble-shooting might go a job.

VII.CONCLUSION

The motives for femtocells include the demand to supply better voice and informations coverage to increasing place users. Femtocells achieve these ends by a combination of frequence reuse, better protection against intervention by runing at parametric quantities assigned by operator. Low power operation reduces wellness issues, similar to bing place and office devices, assisting to see that the devices are acceptable by the users when widely deployed and supplying other benefits as decreased intervention, increased nomadic transmit power and increased battery life. Handover from femto-to-macro is a nucleus issue as this is a necessary process for service continuity, while in the macro-to-femto instance the macro web signal may still be good plenty to supply service indoors. Femtocell market has important challenges and monolithic potency challenges. There is a immense demand for immense investings to bring forth solutions, and there are no warrants over the success of solution from proficient and economic point of view.